3 Carseats across the back

Ive read a few posts about this very topic (3 carseats across the back of the Prius, mine is a 2008 with a hatchback), however, I have yet to read anything about turning off the side curtain airbags. I know three can be done safely with the Diono Radian XRT. I will have 3 under 3 and getting another car is not an option. Anyways, apparently it can be done, but do the side curtain airbags need to be turned off? I realize it is going to be a tight squeeze, so i assume the seats are going to be pretty close to the doors. So my two questions are 1.) do they need turned off and 2.) if they must be turned off, how is that done? I could not locate any information in the manual about it. Will it require a professional? Im all about saving money so if it is something that can be done safety on my own that would be ideal, but obviously saftey is our number one priority.

Ive purchased 3 Diono Radian XRTs. They should be here within a week. I will update, but I just want to make sure everything else is ready.